CN113882459B

CN113882459B - Excavator energy recovery system and excavator

Info

Publication number: CN113882459B
Application number: CN202111156737.9A
Authority: CN
Inventors: 尹超; 曾川; 张云威; 刘贺; 崔广伟; 张升霞; 张俊; 殷想; 王浩
Original assignee: Xuzhou XCMG Excavator Machinery Co Ltd
Current assignee: Xuzhou XCMG Excavator Machinery Co Ltd
Priority date: 2021-09-30
Filing date: 2021-09-30
Publication date: 2023-02-17
Anticipated expiration: 2041-09-30
Also published as: CN113882459A

Abstract

The present disclosure relates to an excavator energy recovery system and excavator, wherein, excavator energy recovery system includes: a boom cylinder (27); a first main pump (22) having a first oil supply line (L1) and a main oil return line (L3), the first oil supply line (L1) being used to supply at least hydraulic oil to a boom cylinder (27); the movable arm descending valve (5) has a connection state and a disconnection state, an oil inlet of the movable arm descending valve (5) is communicated with a rodless cavity of the movable arm oil cylinder (27) through a first oil path (L6), and an oil outlet of the movable arm descending valve (5) is communicated with a main oil return path (L3); and the regeneration valve (4) has a connection state and a disconnection state, an oil inlet of the regeneration valve (4) is communicated with the rodless cavity of the movable arm oil cylinder (27) through a first oil path (L6), and an oil outlet of the regeneration valve (4) is at least communicated with a first oil supply path (L1) through a second oil path (L7), so that the recycling of hydraulic oil in the rodless cavity of the movable arm oil cylinder (27) in the descending process of the movable arm is realized.

Description

Excavator energy recovery system and excavator

Technical Field

The disclosure relates to the technical field of engineering machinery, in particular to an excavator energy recovery system and an excavator.

Background

The hydraulic system of the excavator is used for controlling the actions of a movable arm, an arm and a bucket and enabling the excavator to get on the vehicle to execute a rotation action, and the traditional hydraulic system has the following problems: when the movable arm descends, only a small part of hydraulic oil in the large cavity of the movable arm oil cylinder is regenerated to the small cavity of the movable arm oil cylinder, most of hydraulic oil flows back to the oil tank, flow waste is caused, and power waste is serious in the operation process of the excavator. Disclosure of Invention

The utility model provides an excavator energy recuperation system and excavator can improve the energy utilization of excavator.

According to an aspect of the present disclosure, there is provided an excavator energy recovery system including:

a boom cylinder;

a first main pump having a first oil supply path and a main oil return path, the first oil supply path being configured to supply at least hydraulic oil to the boom cylinder;

the movable arm descending valve has a connection state and a disconnection state, an oil inlet of the movable arm descending valve is communicated with a rodless cavity of the movable arm oil cylinder through a first oil path, and an oil outlet of the movable arm descending valve is communicated with a main oil return oil path; and

the regeneration valve is in a connection state and a disconnection state, an oil inlet of the regeneration valve is communicated with the rodless cavity of the movable arm oil cylinder through a first oil path, and an oil outlet of the regeneration valve is at least communicated with a first oil supply path through a second oil path, so that hydraulic oil in the rodless cavity of the movable arm oil cylinder is recycled in the descending process of the movable arm.

In some embodiments, the excavator energy recovery system further comprises:

a second main pump having a second oil supply path and a main oil return path, the second oil supply path being configured to supply at least hydraulic oil to the boom cylinder; and

and a boom switching valve having a first operation position and a second operation position, and configured to supply hydraulic oil to the rod chamber of the boom cylinder to lower the boom in the first operation position and to supply hydraulic oil to the rodless chamber of the boom cylinder to raise the boom in the second operation position.

In some embodiments, the second oil passage includes:

the first branch oil path is communicated with the first oil supply oil path, and a first one-way valve is arranged on the first branch oil path and is configured to enable the first branch oil path to be communicated from the regeneration valve to the first oil supply oil path in a one-way mode; and

and the second branch oil path is communicated with the second oil supply oil path, and a second one-way valve is arranged on the second branch oil path and is configured to enable the second branch oil path to be communicated from the regeneration valve to the second oil supply oil path in a one-way mode.

In some embodiments, when the regeneration valve is in the on state and the boom reversing valve is in the first working position, the hydraulic oil in the rodless chamber of the boom cylinder is supplemented to the rod chamber of the boom cylinder sequentially through the first oil path, the regeneration valve, the second branch oil path and the boom reversing valve.

In some embodiments, the excavator energy recovery system further comprises a flow regulating valve disposed on the second oil supply line and between the second main pump and the boom reversing valve, configured to regulate flow into the boom reversing valve.

In some embodiments, the excavator energy recovery system further comprises: a pilot pump having a pilot oil supply passage and a pilot oil return passage; the flow control valve includes:

an oil inlet of the third one-way valve is communicated with the second oil supply path, an oil outlet of the third one-way valve is communicated with an oil supply port of the movable arm reversing valve, and the third one-way valve is provided with a spring cavity; and

the hydraulic control regulating valve is provided with a first hydraulic control end and a second hydraulic control end, the first hydraulic control end is communicated with the pilot oil return oil way, and the second hydraulic control end is communicated with the pilot oil supply oil way through the first reversing valve.

In some embodiments, the boom reversing valve has a third pilot controlled end and a fourth pilot controlled end; the excavator energy recovery system further comprises:

a first proportional regulating valve configured to regulate a pilot oil pressure of the third hydraulic control end; and

and a second proportional regulating valve configured to regulate the pilot oil pressure of the fourth hydraulic control port.

In some embodiments, the excavator energy recovery system further comprises: the flow-merging valve is in a connection state and a disconnection state, an oil inlet of the flow-merging valve is communicated with the first oil supply line, and an oil outlet of the flow-merging valve is communicated with an oil inlet of the movable arm descending valve, an oil inlet of the regeneration valve and a rodless cavity of the movable arm oil cylinder;

the oil passing amounts of the movable arm descending valve and the confluence valve are both adjustable.

In some embodiments, the boom lowering valve has a fifth hydraulic control end and a sixth hydraulic control end, the confluence valve has a seventh hydraulic control end and an eighth hydraulic control end, and the excavator energy recovery system further comprises:

a pilot pump having a pilot oil supply passage and a pilot oil return passage;

a third proportional regulating valve configured to regulate a pressure of a fifth hydraulic control end of the boom down valve, the fifth hydraulic control end being connected to the pilot oil supply passage, and the sixth hydraulic control end being connected to the pilot oil return passage; and

and the fourth proportional regulating valve is configured to regulate the pressure of an eighth hydraulic control end of the confluence valve, the seventh hydraulic control end is connected with the pilot oil return oil way, and the eighth hydraulic control end is connected with the pilot oil supply oil way.

In some embodiments, the excavator energy recovery system further comprises:

a bucket rod cylinder;

the first bucket rod reversing valve is arranged on the first oil supply oil way and is configured to control the bucket rod oil cylinder to stretch and retract; and

and the second arm reversing valve is arranged on the second oil supply oil path and is configured to control the arm oil cylinder to stretch.

In some embodiments, the first bucket rod reversing valve and the second bucket rod reversing valve are both provided with a first oil return port and a second oil return port, a first throttling element is connected between the first oil return port and the second oil return port of the first bucket rod reversing valve in a middle position, and the main oil return path is provided with a first branch oil return path and a second branch oil return path downstream of the oil outlet of the boom descending valve; wherein,

the first branch oil return path is provided with a radiator and is connected with an oil tank through the radiator; the second branch oil return path is connected with the oil tank through the first oil return port, the first throttling element and the second oil return port in sequence, the first oil return port of the second bucket rod reversing valve is communicated with the first branch oil return path, and the second oil return port of the second bucket rod reversing valve is communicated with the second branch oil return path.

In some embodiments, the first bucket rod reversing valve and the second bucket rod reversing valve are provided with an oil supply port, a first working oil port, a second working oil port and a third working oil port;

when the first bucket rod reversing valve is in the inward contraction working position, the first working oil port is communicated with the oil supply port and a rodless cavity of the bucket rod oil cylinder, the second working oil port is communicated with a rod cavity of the bucket rod oil cylinder, and the third working oil port is communicated with the second working oil port;

when the second bucket rod reversing valve is located at the middle position, a first working oil port of the second bucket rod reversing valve is communicated with a rodless cavity of the bucket rod oil cylinder, a second working oil port of the second bucket rod reversing valve is communicated with a third working oil port of the first bucket rod reversing valve and communicated with a first working oil port of the second bucket rod reversing valve through a second throttling element, and the third working oil port, an oil supply port, a first oil return port and a second oil return port of the second bucket rod reversing valve are all cut off.

when the first bucket rod reversing valve is in the inward-retracting working position, the first working oil port is communicated with the oil supply port and a rodless cavity of the bucket rod oil cylinder, the second working oil port is communicated with a rod cavity of the bucket rod oil cylinder, the third working oil port is communicated with the second working oil port, and the third working oil port enables hydraulic oil to return to the rodless cavity of the bucket rod oil cylinder through the middle position of the second bucket rod reversing valve.

In some embodiments, when the second arm reversing valve is in the first retracted working position, the oil supply port of the second arm reversing valve is communicated with the rodless cavity of the arm cylinder through the first working oil port, the second working oil port of the second arm reversing valve is communicated with the third working oil port of the first arm reversing valve, and is communicated with the first oil return port of the second arm reversing valve, which is connected to the first branch oil return path, and a third throttling element is arranged between the second working oil port and the first oil return port of the second arm reversing valve.

In some embodiments, when the second arm reversing valve is in the second retracted working position, the oil supply port of the second arm reversing valve is communicated with the rodless cavity of the arm cylinder through the first working oil port, the second working oil port of the second arm reversing valve is communicated with the third working oil port of the first arm reversing valve and is communicated with the first oil return port of the second arm reversing valve connected to the first branch oil return path, a third throttling element and a sixth check valve are arranged between the second working oil port of the second arm reversing valve and the first oil return port, the sixth check valve is configured to only allow hydraulic oil to flow from the second working oil port to the first oil return port, and the third working oil port of the second arm reversing valve is communicated with the first oil return port.

In some embodiments, when the second arm reversing valve is in the first retracted working position and the second retracted working position, a fourth check valve is arranged on an oil path between the first working oil port and the second working oil port of the second arm reversing valve and configured to only allow oil to flow from the second working oil port to the first working oil port.

According to another aspect of the present disclosure, there is provided an excavator comprising the excavator energy recovery system of the above embodiment.

In the excavator energy recovery system according to the embodiment of the disclosure, in the process that the movable arm cylinder retracts to enable the movable arm to descend, if the movable arm descending valve is in a connected state, hydraulic oil in a rodless cavity of the movable arm cylinder enters the main oil return oil circuit through the movable arm descending valve and returns to the oil tank; if the regeneration valve is in a connected state, hydraulic oil in the rodless cavity of the boom cylinder at least enters the first oil supply path through the regeneration valve so as to drive other actuating mechanisms in the excavator, wherein the other actuating mechanisms can be an arm cylinder, a bucket cylinder, a rotary motor and the like, or hydraulic oil can be supplemented to the rod cavity of the boom cylinder, so that the recovery and reutilization of boom descending energy can be realized, the energy loss is reduced, and the energy utilization rate of the whole hydraulic system is improved.

Drawings

In order to more clearly illustrate the embodiments of the present disclosure or the technical solutions in the prior art, the drawings needed to be used in the description of the embodiments or the prior art will be briefly introduced below, it is obvious that the drawings in the following description are only some embodiments of the present disclosure, and for those skilled in the art, other drawings can be obtained according to the drawings without inventive exercise.

Fig. 1 is a hydraulic system schematic of some embodiments of the excavator energy recovery system of the present disclosure.

FIG. 2 is a schematic diagram of some embodiments of a first stick diverter valve.

FIG. 3 is a schematic diagram of some embodiments of a second stick diverter valve.

Detailed Description

The technical solutions in the embodiments of the present disclosure will be described clearly and completely with reference to the drawings in the embodiments of the present disclosure, and it is obvious that the embodiments described are only some embodiments of the present disclosure, rather than all embodiments. The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the disclosure, its application, or uses. All other embodiments, which can be derived by a person skilled in the art from the embodiments disclosed herein without any inventive step, are intended to be within the scope of the present disclosure.

Techniques, methods, and apparatus known to those of ordinary skill in the relevant art may not be discussed in detail, but are intended to be part of the specification where appropriate.

In the description of the present disclosure, it is to be understood that the orientation or positional relationship indicated by the directional terms such as "front, rear, upper, lower, left, right", "lateral, vertical, horizontal" and "top, bottom", etc., are generally based on the orientation or positional relationship shown in the drawings, and are presented only for the convenience of describing and simplifying the disclosure, and in the absence of a contrary indication, these directional terms are not intended to indicate and imply that the device or element being referred to must have a particular orientation or be constructed and operated in a particular orientation, and therefore, should not be taken as limiting the scope of the disclosure; the terms "inner and outer" refer to the inner and outer relative to the profile of the respective component itself.

In the description of the present disclosure, it should be understood that the terms "first", "second", etc. are used to define the components, and are used only for convenience of distinguishing the corresponding components, and if not otherwise stated, the terms have no special meaning, and thus, should not be construed as limiting the scope of the present disclosure.

As shown in fig. 1, the present disclosure provides an excavator energy recovery system, comprising, in some embodiments: a boom cylinder 27, a first main pump 22, a boom lowering valve 5, and a regeneration valve 4.

A boom cylinder 27, which may be provided in one or two, configured to control the raising and lowering of the boom;

the first main pump 22, which may be a variable displacement pump, has a first oil supply path L1 and a main oil return path L3, and the first oil supply path L1 is configured to supply at least the boom cylinder 27 with hydraulic oil, and optionally, the first main pump 22 may also supply hydraulic oil to the arm cylinder 28, the bucket cylinder, the swing motor, and the like.

The boom lowering valve 5, which may be an on-off valve, has an on state and an off state, an oil inlet of the boom lowering valve 5 is communicated with the rodless chamber of the boom cylinder 27 through a first oil path L6, and an oil outlet of the boom lowering valve 5 is communicated with the main oil return path L3.

The regeneration valve 4 can be an on-off valve and has an on state and an off state, an oil inlet of the regeneration valve 4 is communicated with the rodless cavity of the boom cylinder 27 through a first oil path L6, and an oil outlet of the regeneration valve 4 is at least communicated with the first oil supply path L1 through a second oil path L7, so that the recycling of hydraulic oil in the rodless cavity of the boom cylinder 27 in the boom descending process is realized.

In the process that the boom cylinder retracts to enable the boom to descend, if the boom descending valve 5 is in a connected state, hydraulic oil in a rodless cavity of the boom cylinder 27 enters the main oil return path L3 through the boom descending valve 5 and returns to the oil tank; if the regeneration valve 4 is in the on state and the boom lowering valve 5 is in the off state, the hydraulic oil in the rodless cavity of the boom cylinder 27 passes through the regeneration valve 4 and enters at least the first oil supply path L1 to drive other actuators in the excavator, where the other actuators may be an arm cylinder 28, a bucket cylinder, a swing motor, and the like, or the hydraulic oil may be supplemented to the rod cavity of the boom cylinder 27, so that the boom lowering energy can be recycled, the energy loss can be reduced, and the energy utilization rate of the whole hydraulic system can be improved.

According to the operation requirement, the boom descending valve 5 can be in a connection state, the regeneration valve 4 is in a disconnection state, and all hydraulic oil in the rodless cavity of the boom cylinder 27 returns to the oil tank; or the boom lowering valve 5 is in an off state, and the regeneration valve 4 is in an on state, so that all the hydraulic oil in the rodless cavity of the boom cylinder 27 is recycled; or the boom descending valve 5 and the regeneration valve 4 are both in a connected state, so that part of the hydraulic oil in the rodless cavity of the boom cylinder 27 returns to the oil tank, and the other part is recycled.

As shown in fig. 1, the excavator energy recovery system further includes a ninth proportional control valve 8 for adjusting the pressure of the pilot oil at the pilot control end of the regeneration valve 4 to adjust the flow rate of the pilot oil flowing through the regeneration valve 4 during the boom descending process, so as to control the flow rate of the hydraulic oil supplied to other actuators or rod chambers of the boom cylinder 27 during the boom descending process, thereby realizing the required distribution of the regeneration energy. Furthermore, when the boom is lowered, the regeneration valve 4 for recovering and utilizing energy is provided outside the boom control valve, so that maintenance is easy, and normal use of the boom control function is not affected even if a problem occurs in the regeneration function.

In some embodiments, the excavator energy recovery system further comprises: a second main pump 23 and a boom switch valve 18.

A second main pump 23, which may be a variable pump, having a second oil supply path L2 and a main oil return path L3, the second oil supply path L2 being configured to supply at least hydraulic oil to the boom cylinder 27; alternatively, the second main pump 23 may supply hydraulic oil to the arm cylinder 28, the bucket cylinder, the swing motor, and the like.

The boom switching valve 18, which may be a three-position four-way switching valve, has a first operating position and a second operating position, and is configured to supply hydraulic oil to a rod chamber of the boom cylinder 27 to lower the boom in the first operating position and to supply hydraulic oil to a rodless chamber of the boom cylinder 27 to raise the boom in the second operating position. Alternatively, the boom switching valve 18 may also have a neutral position in which the boom cylinder 27 is in a stationary state.

The embodiment can provide hydraulic oil for the boom cylinder 27 or other actuators through the first main pump 22 and the second main pump 23, and can provide more sufficient power for the operation of the excavator, thereby meeting the work requirement of the excavator.

In some embodiments, as shown in fig. 1, the second oil passage L7 includes:

a first branch oil passage L71 communicating with the first oil supply passage L1, the first branch oil passage L71 being provided with a first check valve 41 configured to allow the first branch oil passage L71 to communicate unidirectionally from the regeneration valve 4 to the first oil supply passage L1; and

the second branch oil passage L72 is communicated with the second oil supply passage L2, and the second branch oil passage L72 is provided with a second check valve 42 configured to allow the second branch oil passage L72 to be communicated in one direction from the regeneration valve 4 to the second oil supply passage L2.

Alternatively, a one-end common oil passage may be further provided upstream of the first branch oil passage L71 and the second branch oil passage L72, and a first end of the common oil passage communicates with the oil outlet of the regeneration valve 4 and a second end communicates with the first branch oil passage L71 and the second branch oil passage L72.

In this embodiment, the oil path after passing through the regeneration valve 4 is simultaneously communicated with the first oil supply path L1 and the second oil supply path L2, so that the hydraulic oil in the rodless chamber of the boom cylinder 27 during the lowering of the boom can be simultaneously introduced into the first oil supply path L1 and the second oil supply path L2, and can be utilized by various actuators connected to the first oil supply path L1 and the second oil supply path L2, thereby more flexibly achieving the recycling of the boom lowering energy.

In some embodiments, when the regeneration valve 4 is in the on state and the boom changing valve 18 is in the first operating position, the hydraulic oil in the rodless chamber of the boom cylinder 27 is replenished to the rod chamber of the boom cylinder 27 through the first oil passage L6, the regeneration valve 4, the second branch oil passage L72, and the boom changing valve 18 in this order.

According to the embodiment, the hydraulic oil in the rodless cavity of the boom cylinder 27 can be supplemented into the rod cavity in the boom descending process, so that the oil supply amount of the main pump in the boom descending process can be reduced, the boom descending energy can be recycled, and the overall energy consumption of the hydraulic system can be reduced.

In some embodiments, the excavator energy recovery system further includes a flow regulating valve 17 provided on the second oil supply path L2 and located between the second main pump 23 and the boom switching valve 18, configured to regulate a flow into the boom switching valve 18. For example, the flow rate adjustment valve 17 has an electric proportional control function.

In the embodiment, the flow regulating valve 17 is arranged at the oil supply port of the movable arm reversing valve 18, when a movable arm descends and other actuators such as an arm and the like act simultaneously, due to the fact that the weight of the whole machine is large, the flow required by a rod cavity of the movable arm oil cylinder 27 is small, and in order to reduce the descending speed of the movable arm, according to different working condition requirements, the flow entering the movable arm reversing valve 18 can be controlled through the flow regulating valve 17, redundant flow enters other actuators, the priority of the other actuators is improved, and meanwhile, the flow entering the movable arm reversing valve 18 is controlled, so that energy consumption is reduced.

Further, when the boom descends, the flow rate control valve 17 prevents the supply of oil to the boom switching valve 18, the boom descends by regenerative oil supply to the boom, and the hydraulic oil of the second main pump 23 is supplied to other actuators such as an arm, thereby increasing the operating speed and the coordination such as the swing-out and the like associated with the boom descent, and saving energy.

During the boom rising process, the oil inlet amount of the boom reversing valve 18 is controlled through the flow regulating valve 17, so that the boom rising speed is controlled, redundant hydraulic oil flows to other actuators such as an arm, and the coordination of actions such as retraction, flat ground and the like related to the boom rising is improved.

In some embodiments, as shown in fig. 1, the excavator energy recovery system further comprises: a pilot pump 24, which may be a gear pump, having a pilot oil supply passage L4 and a pilot oil return passage L5; a second directional valve 15, for example, a two-position three-way electromagnetic directional valve, may be provided on the pilot oil supply passage L4, and is configured to turn on the pilot oil passage in an energized state and turn off the pilot oil passage in a de-energized state, and corresponds to a pilot pressure switch. The flow rate regulating valve 17 includes: a third check valve 171 and a pilot operated regulator valve 172.

An oil inlet of the third check valve 171 is communicated with the second oil supply path L2, specifically, the second branch oil path L72, an oil outlet of the third check valve 171 is communicated with an oil supply port of the movable arm directional control valve 18, and the third check valve 171 has a spring cavity which may be disposed opposite to the oil inlet.

The hydraulic control regulating valve 172 may be an on-off valve having an on state and an off state, an oil inlet of the hydraulic control regulating valve 172 is communicated with the spring cavity, an oil outlet of the hydraulic control regulating valve 172 is communicated with an oil supply port of the movable arm directional control valve 18, the hydraulic control regulating valve 172 has a first hydraulic control end a and a second hydraulic control end B, the first hydraulic control end a is communicated with the pilot oil return path L5, and the second hydraulic control end B is communicated with the pilot oil supply path L4 through the first directional control valve 16. For example, the first direction valve 16 may be a two-position three-way electromagnetic direction valve, and has an electrical proportional adjustment function in a state where the pilot oil supply path L4 is connected, the oil supply port of the first direction valve 16 is communicated with the pilot oil supply path L4, the oil return port is communicated with the pilot oil return path L5, and the working oil port is communicated with the second hydraulic control port B.

In this embodiment, the opening size of the pilot-operated control valve 172 can be adjusted by the pressure of the pilot oil supply passage L4 to adjust the pressure of the spring chamber, thereby adjusting the opening size of the third check valve 171 and thus adjusting the flow rate into the boom switching valve 18. When the boom and other actuators such as the arm act simultaneously, the flow entering the boom reversing valve 18 can be adjusted according to different working condition requirements, so that the boom speed is reduced, redundant flow enters other actuators, and the action coordination is optimized.

In some embodiments, the boom directional control valve 18 has a third pilot controlled end C and a fourth pilot controlled end D; the excavator energy recovery system further comprises: a first proportional regulating valve 13 configured to regulate the pilot oil pressure of the third pilot control port C; and a second proportional regulating valve 14 configured to regulate the pilot oil pressure of the fourth hydraulic control port D.

For example, the first proportional regulating valve 13 and the second proportional regulating valve 14 are two-position three-way electric proportional reducing valves having an energized state and a de-energized state, and have oil supply ports connected to the pilot oil supply passage L4 and oil return ports communicated to the pilot oil return passage L5. The working oil port of the first proportional regulating valve 13 communicates with the third hydraulic control port C, the pilot oil is supplied to the third hydraulic control port C when the first proportional regulating valve 13 is in the energized state, and the third hydraulic control port C communicates with the pilot oil return passage L5 when the first proportional regulating valve 13 is in the de-energized state; the working oil port of the second proportional control valve 14 is communicated with the fourth hydraulic control end D, and when the second proportional control valve 14 is in the energized state, the pilot oil is supplied to the fourth hydraulic control end D, and the fourth hydraulic control end D is communicated with the pilot oil return path L5.

The embodiment can control the descending speed of the boom as required through the first proportional control valve 13 and control the ascending speed of the boom as required through the second proportional control valve 14, thereby realizing the accurate control of the boom working speed to meet the working requirements under different working conditions.

In some embodiments, the excavator energy recovery system further comprises: the flow-merging valve 3 has a connection state and a disconnection state, an oil inlet of the flow-merging valve 3 is communicated with the first oil supply path L1, and an oil outlet of the flow-merging valve 3 is communicated with an oil inlet of the movable arm descending valve 5, an oil inlet of the regeneration valve 4 and a rodless cavity of the movable arm oil cylinder 27; the oil passing amounts of the regeneration valve 4, the movable arm descending valve 5 and the flow converging valve 3 are all adjustable.

In this embodiment, when the boom cylinder 27 is supplied with oil by the first main pump 22 and the second main pump 23, the boom switching valve corresponding to the first main pump 22 in the related art is divided into the confluence valve 3 and the boom lowering valve 5, the boom raising is controlled by the confluence valve 3, and the boom lowering 5 is controlled by the boom lowering valve 5. Therefore, the ratio of the oil inlet area to the oil return area can be adjusted according to actual needs, and the opening area of the valve core for controlling the movable arm to ascend and the movable arm to descend is further controlled according to needs. Aiming at different working conditions such as excavation, unloading, flat ground and the like, different opening area ratios are set, and the oil consumption, the efficiency and the operation coordination of the whole machine are improved.

In the system, the ratio of the oil inlet area to the oil return area can be adjusted only by splitting the boom reversing valve corresponding to one of the main pumps into the confluence valve 3 and the boom lowering valve 5, and optionally, the boom regulating valves 18 corresponding to the first main pump 22 and the second main pump 23 can be split into the confluence valve 3 and the boom lowering valve 5, so as to adjust the ratio in a wider range.

In some embodiments, the boom down valve 5 has a fifth hydraulic control port E and a sixth hydraulic control port F, the fifth hydraulic control port E communicates with the pilot oil return path L5, and the sixth hydraulic control port F communicates with the pilot oil return path L5. The confluence valve 3 has a seventh hydraulic control end G and an eighth hydraulic control end H, the seventh hydraulic control end G is communicated with the pilot oil return path L5, and the eighth hydraulic control end H is communicated with the pilot oil return path L5. The excavator energy recovery system further comprises: a third proportional regulating valve 7 configured to regulate a pressure of the fifth hydraulic control port E of the boom-down valve 5; and a fourth proportional regulating valve 6 configured to regulate the pressure of the eighth pilot-controlled port H of the confluence valve 3. Specifically, the fifth hydraulic control end E communicates with the pilot oil return passage L5 through the third proportional control valve 7, and the eighth hydraulic control end H communicates with the pilot oil return passage L5 through the fourth proportional control valve 6.

This embodiment can accurately adjust the lowering speed of the boom by providing the boom-lowering valve 5 with the third proportional regulating valve 7, and can accurately adjust the raising speed of the boom by providing the confluence valve 3 with the fourth proportional regulating valve 6. And moreover, the ratio of the oil inlet area to the oil return area can be adjusted according to actual needs, and further the opening areas of the valve cores for lifting the movable arm and lowering the movable arm can be controlled according to needs. Aiming at different working conditions such as excavation, unloading, flat ground and the like, different opening area ratios are set, and the oil consumption, the efficiency and the operation coordination of the whole machine are improved.

During boom lowering, the boom lowering speed can be adjusted by both the first proportional control valve 13 and the third proportional control valve 7, and the adjustment range of the boom lowering speed can be expanded. Further, the boom lowering speed can also be adjusted by the regeneration valve 4 and the flow rate adjustment valve 17.

In some embodiments, the excavator energy recovery system of the present disclosure further comprises: arm cylinder 28, first arm directional control valve 9, and second arm directional control valve 31. The bucket rod oil cylinder 28 is used for controlling the bucket rod to retract and release; the first arm directional control valve 9 is provided on the first oil supply path L1, and is configured to control the arm cylinder 28 to extend and retract; second arm switching valve 31 is provided on second oil supply passage L2, and is configured to control extension and contraction of arm cylinder 28.

In the process that the boom cylinder retracts to enable the boom to descend, if the boom descending valve 5 is in a connected state, hydraulic oil in a rodless cavity of the boom cylinder 27 enters the main oil return path L3 through the boom descending valve 5 and returns to the oil tank; if the regeneration valve 4 is in the on state, the hydraulic oil in the rodless chamber of the boom cylinder 27 may enter the first oil supply passage L1 and the second oil supply passage L2 through the regeneration valve 4 to drive the arm cylinder 28. Therefore, the boom-lowering energy can be recycled, so that the energy loss is reduced, and the energy utilization rate of the whole hydraulic system is improved.

In some embodiments, as shown in fig. 1 to 3, each of the first arm reversing valve 9 and the second arm reversing valve 31 is provided with a first oil return port T1 and a second oil return port T2, a first throttling element 91, such as a throttle valve, is connected between the first oil return port T1 and the second oil return port T2 of the first arm reversing valve 9 at the middle position W2, and the main oil return path L3 is provided with a first branch oil return path L31 and a second branch oil return path L32 downstream of the oil outlet of the boom lowering valve 5.

Wherein, the first branch oil return path L31 is provided with a radiator 29, and the first branch oil return path L31 is connected with the oil tank 30 through the radiator 29; the second branch oil return path L32 is connected to the oil tank 30 through a first oil return port T1, a first throttling element 91 and a second oil return port T2 in sequence, the first oil return port T1 of the second arm reversing valve 31 is communicated with the first branch oil return path L31, and the second oil return port T2 of the second arm reversing valve 31 is communicated with the second branch oil return path L32.

When the first bucket rod reversing valve 9 is located at the middle position W2, the oil supply port P, the first working oil port M, the second working oil port N and the third working oil port O are all cut off. In the embodiment, two branch oil return paths are arranged, when the arm cylinder 28 does not work or the whole machine executing mechanism does not work, as the system generates less heat, part of hydraulic oil can return through the second branch oil return path L32, and in the oil return process, the pressure of a rod cavity of the arm cylinder 28 can be controlled under the throttling action of the first throttling element 91, so that the retraction speed of the arm is stable; and the hydraulic oil can be heated, so that the hydraulic oil can be kept at a proper temperature after the excavator starts to work, the corresponding sensitivity of the system is improved, the action delay is shortened, the oil absorption resistance of the pump can be reduced, the air suction is prevented, and the excavator can work in a low-temperature environment. In the working process of the first bucket rod reversing valve 9, the heat productivity of the system is relatively large, the first throttling element 91 does not work, and the hydraulic oil directly returns to the oil tank 30 through the first branch oil return path L31.

In some embodiments, the first arm reversing valve 9 and the second arm reversing valve 31 are provided with an oil supply port P, a first working oil port M, a second working oil port N, and a third working oil port O.

When the first arm reversing valve 9 is in the retracted working position W1, the first working oil port M is communicated with the oil supply port P and the rodless cavity of the arm cylinder 28, the second working oil port N is communicated with the rod cavity of the arm cylinder 28, the third working oil port O is communicated with the second working oil port N, and the first oil return port T1 and the second oil return port T2 are closed. When the first arm switching valve 9 is in the retracted working position W1, it is necessary to perform the retracting operation in cooperation with the second arm switching valve 31 being in the neutral position W2.

When the second arm directional control valve 31 is located at the middle position W2, the first working oil port M of the second arm directional control valve 31 is communicated with the rodless cavity of the arm cylinder 28, the second working oil port N of the second arm directional control valve 31 is communicated with the third working oil port O of the first arm directional control valve 9, and is communicated with the first working oil port M of the second arm directional control valve 31 through the second throttling element 311, and the third working oil port O, the oil supply port P, the first oil return port T1, and the second oil return port T2 of the second arm directional control valve 31 are all cut off. Optionally, a fifth check valve 314 may be disposed between the first working port M and the second working port N of the second arm reversing valve 31, and configured to allow only one-way flow of the hydraulic oil from the second working port N to the first working port M.

In this embodiment, when the first arm reversing valve 9 is located at the adduction operating position W1, it is necessary to perform adduction by cooperating with the second arm reversing valve 31 at the middle position W2, specifically, hydraulic oil enters the rodless cavity of the arm cylinder 28 through the oil inlet of the first arm reversing valve 9, and the hydraulic oil in the rod cavity returns to the rodless cavity of the arm cylinder 28 through the second operating oil port N of the second arm reversing valve 31, the second throttling element 311, the fifth check valve 314, and the first operating oil port M in sequence for recycling, so that energy of the hydraulic system can be saved.

Further, the first arm reversing valve 9 further includes an outward swing working position W3, the oil supply port P communicates with the rod chamber of the arm cylinder 28, and the rodless chamber of the arm cylinder 28 communicates with the second branch oil return path L32 through the first working oil port M and the second oil return T2.

In some embodiments, the first arm reversing valve 9 and the second arm reversing valve 31 are provided with an oil supply port P, a first working oil port M, a second working oil port N, and a third working oil port O; when the first arm directional control valve 9 is in the retracted working position W1, the first working oil port M is communicated with the oil supply port P and the rodless cavity of the arm cylinder 28, the second working oil port N is communicated with the rod cavity of the arm cylinder 28, the third working oil port O is communicated with the second working oil port N, and the third working oil port O returns hydraulic oil to the rodless cavity of the arm cylinder 28 through the middle position W2 of the second arm directional control valve 31.

In some embodiments, when the second arm reversing valve 31 is in the first retracted working position W4, the oil supply port P of the second arm reversing valve 31 is communicated with the rodless cavity of the arm cylinder 28 through the first working oil port M, the second working oil port N of the second arm reversing valve 31 is communicated with the third working oil port O of the first arm reversing valve 9 and is communicated with the first oil return port T1 of the second arm reversing valve 31 connected to the first branch oil return line L31, a third throttling element 312 and a sixth check valve 315 are disposed between the second working oil port N of the second arm reversing valve 31 and the first oil return port T1, and the sixth check valve 315 is configured to allow only hydraulic oil to flow from the second working oil port N to the first oil return port T1. The second oil return port T2 and the third working oil port O of the second arm reversing valve 31 are in a cut-off state. Optionally, a check valve may be further disposed on an oil path between the first oil return port T1 and the second working oil port N of the second arm reversing valve 31, and configured to allow only one-way flow of hydraulic oil from the second working oil port N to the first oil return port T1.

In this embodiment, when the arm is retracted, oil is returned through the first retracted position W4 of the second arm reversing valve 31, and since the third throttling element 272 can generate oil return back pressure, the arm is retracted smoothly, and the operation coordination is improved.

In some embodiments, when the second arm reversing valve 31 is in the second retracted working position W5, the oil supply port P of the second arm reversing valve 31 is communicated with the rodless cavity of the arm cylinder 28 through the first working oil port M, the second working oil port N of the second arm reversing valve 31 is communicated with the third working oil port O of the first arm reversing valve 9 and is communicated with the first oil return port T1 of the second arm reversing valve 31 connected to the first branch oil return path L31, a third throttling element 312 is disposed between the second working oil port N of the second arm reversing valve 31 and the first oil return port T1, and the third working oil port O of the second arm reversing valve 31 is communicated with the first oil return port T1. Optionally, a check valve may be further disposed on an oil path between the first oil return port T1 and the second working oil port N of the second arm reversing valve 31, and configured to allow only one-way flow of hydraulic oil from the second working oil port N to the first oil return port T1.

In this embodiment, when the arm is retracted, oil is returned through the second retracted position W5 of the second arm switching valve 31, and since no orifice is provided in the oil return passage, the pressure of the returned oil is reduced, and the excavating capacity of the excavator is improved.

In some embodiments, when the second arm reversing valve 31 is located at the first and second inward retracting work positions W4 and W5, a fourth check valve 313 is provided on an oil path between the first and second work ports M and N of the second arm reversing valve 31, and is configured to allow only oil to flow from the second work port N to the first work port M.

In the process of returning oil through the second arm reversing valve 31, a part of hydraulic oil is allowed to enter the rodless cavity of the arm cylinder 28 through the fourth check valve 313 and the first working oil port M, and the hydraulic oil can be recycled.

Further, the second arm reversing valve 31 further includes an outward swing working position W1, the oil supply port P is communicated with the rod chamber of the arm cylinder 28 through the third working oil port O, and the rodless chamber of the arm cylinder 28 is communicated with the second branch oil return path L32 through the first working oil port M and the second oil return port T2. When the bucket rod swings outwards, the bucket rod oil cylinder retracts.

In this embodiment, when the arm swings outward, the hydraulic oil can be directly returned to the oil tank 30 through the second branch oil return path L32 without passing through the radiator 29, and the pressure loss can be reduced.

In some embodiments, the first stick divert valve 9 and the second stick divert valve 31 each have a ninth pilot controlled end I and a tenth pilot controlled end J; the excavator energy recovery system further comprises: a fifth proportional regulating valve 12 configured to regulate the pilot oil pressure of the ninth hydraulic control end I of the first bucket rod reversing valve 9; a sixth proportional regulating valve 11 configured to regulate the pilot oil pressure of the tenth hydraulic control end J of the first stick switch valve 9; a seventh proportional regulating valve 25 configured to regulate the pilot oil pressure of the ninth pilot-operated end I of the second arm switching valve 31; and an eighth proportional regulating valve 26 configured to regulate the pilot oil pressure at the tenth pilot control end J of the second arm switching valve 31.

For example, the fifth proportional control valve 12, the sixth proportional control valve 11, the seventh proportional control valve 25, and the eighth proportional control valve 26 are two-way three-way electric proportional pressure reducing valves having an energized state and a de-energized state, and the oil supply ports thereof are connected to the pilot oil supply line L4 and the oil return ports thereof are communicated with the pilot oil return line L5.

The working oil port of the fifth proportional control valve 12 is communicated with the ninth hydraulic control end I of the first bucket rod reversing valve 9, when the fifth proportional control valve 12 is in a power-on state, the pilot oil is supplied to the ninth hydraulic control end I of the first bucket rod reversing valve 9, and when the fifth proportional control valve 12 is in a power-off state, the ninth hydraulic control end I of the first bucket rod reversing valve 9 is communicated with the pilot oil return path L5. The fifth proportional control valve 12 is used to adjust the piston rod extension speed of the arm cylinder 28 to adjust the retraction speed of the arm.

The working oil port of the sixth proportional control valve 11 is communicated with the tenth hydraulic control end J of the first bucket rod reversing valve 9, when the sixth proportional control valve 11 is in a power-on state, the pilot oil is supplied to the tenth hydraulic control end J of the first bucket rod reversing valve 9, and when the sixth proportional control valve 11 is in a power-off state, the tenth hydraulic control end J of the first bucket rod reversing valve 9 is communicated with the pilot oil return path L5. The sixth proportional control valve 11 is used for adjusting the piston rod retraction speed of the arm cylinder 28 to adjust the swing-out speed of the arm.

The working oil port of the seventh proportional control valve 25 is communicated with the ninth hydraulic control end I of the second arm directional control valve 31, when the seventh proportional control valve 25 is in the energized state, the pilot oil is supplied to the ninth hydraulic control end I of the second arm directional control valve 31, and when the seventh proportional control valve 25 is in the de-energized state, the ninth hydraulic control end I of the second arm directional control valve 31 is communicated with the pilot oil return path L5. The seventh proportional control valve 25 is used to adjust the piston rod extension speed of the arm cylinder 28 to adjust the retraction speed of the arm.

The working oil port of the eighth proportional control valve 26 is communicated with the tenth hydraulic control end J of the second arm directional control valve 31, the pilot oil is supplied to the tenth hydraulic control end J of the second arm directional control valve 31 when the eighth proportional control valve 26 is in the energized state, and the tenth hydraulic control end J of the second arm directional control valve 31 is communicated with the pilot oil return path L5 when the eighth proportional control valve 26 is in the de-energized state. The eighth proportional control valve 26 is used for adjusting the piston rod retraction speed of the arm cylinder 28 to adjust the swing-out speed of the arm.

According to the embodiment, the retraction speed of the arm can be controlled through the fifth proportion regulating valve 12, the sixth proportion regulating valve 11, the seventh proportion regulating valve 26 and the eighth proportion regulating valve 25, so that the operation speed of the arm can be accurately controlled, and the operation requirements under different working conditions can be met.

Optionally, the excavator energy recovery system further includes a first unloading valve 2 and a tenth proportional regulating valve 1, the first unloading valve 2 is disposed on the first oil supply line L1, an on-off valve may be used, and the tenth proportional regulating valve 1 is configured to regulate the pressure of the pilot oil at the pilot control end of the first unloading valve 2 to regulate the unloading pressure of the first main pump 22.

Optionally, the excavator energy recovery system further includes a second unloading valve 21 and an eleventh proportional regulating valve 20, the second unloading valve 21 is provided on the second oil supply path L2, an on-off valve may be adopted, and the eleventh proportional regulating valve 20 is configured to regulate the pressure of the pilot oil at the pilot control end of the second unloading valve 21 to regulate the unloading pressure of the second main pump 23.

Alternatively, the pilot oil supply passage L4 may be provided with a relief valve 10 to relief when the pressure of the pilot oil supply passage L4 exceeds a preset pressure.

The tenth proportional control valve 1, the first direction changing valve 16 and the eleventh proportional control valve 20 are not controlled by the second direction changing valve 15, and can work under the condition that the safety handle is powered off.

Secondly, this disclosure provides an excavator, including the excavator energy recuperation system of above-mentioned embodiment.

The above description is intended only to illustrate embodiments of the present disclosure, and should not be taken as limiting the disclosure, and any modifications, equivalents, improvements and the like made within the spirit and principle of the present disclosure should be included in the scope of the present disclosure.

Claims

1. An excavator energy recovery system, comprising:

a boom cylinder (27);

a first main pump (22) having a first oil supply path (L1) and a main oil return path (L3), the first oil supply path (L1) being configured to supply at least the boom cylinder (27) with hydraulic oil;

the movable arm descending valve (5) is in a connection state and a disconnection state, an oil inlet of the movable arm descending valve (5) is communicated with a rodless cavity of the movable arm oil cylinder (27) through a first oil path (L6), and an oil outlet of the movable arm descending valve (5) is communicated with the main oil return path (L3); and

the regeneration valve (4) is in a connection state and a disconnection state, an oil inlet of the regeneration valve (4) is communicated with a rodless cavity of the movable arm oil cylinder (27) through the first oil path (L6), an oil outlet of the regeneration valve (4) is at least communicated with the first oil supply path (L1) through a second oil path (L7), so that hydraulic oil in the rodless cavity of the movable arm oil cylinder (27) is recycled in the descending process of the movable arm, and the hydraulic oil is supplemented to a rod cavity of the movable arm oil cylinder or drives other execution mechanisms;

under the condition that the movable arm descending valve (5) is in a connection state and the regeneration valve (4) is in a disconnection state, all hydraulic oil in a rodless cavity of the movable arm oil cylinder (27) returns to the oil tank (30); under the condition that the boom descending valve (5) is in a disconnected state and the regeneration valve (4) is in a connected state, all hydraulic oil in a rodless cavity of the boom oil cylinder (27) is recycled; and under the condition that the boom descending valve (5) and the regeneration valve (4) are both in a communicated state, part of the hydraulic oil in the rodless cavity of the boom cylinder (27) returns to the oil tank (30), and the other part is recycled.

2. The excavator energy recovery system of claim 1, further comprising:

a second main pump (23) having a second oil supply path (L2) and the main oil return path (L3), the second oil supply path (L2) being configured to supply at least the boom cylinder (27) with hydraulic oil; and

a boom directional control valve (18) having a first working position and a second working position, and configured to supply hydraulic oil to a rod chamber of the boom cylinder (27) to lower the boom in the first working position, and to supply hydraulic oil to a rodless chamber of the boom cylinder (27) to raise the boom in the second working position.

3. The excavator energy recovery system of claim 2, wherein the second oil passage (L7) comprises:

a first branch oil passage (L71) that communicates with the first oil supply passage (L1), the first branch oil passage (L71) being provided with a first check valve (41) configured to allow the first branch oil passage (L71) to communicate unidirectionally from the regeneration valve (4) to the first oil supply passage (L1); and

and a second branch oil path (L72) that communicates with the second oil supply path (L2), wherein a second check valve (42) is provided in the second branch oil path (L72) and is configured to allow the second branch oil path (L72) to be communicated in one direction from the regeneration valve (4) to the second oil supply path (L2).

4. The excavator energy recovery system according to claim 3, wherein when the regeneration valve (4) is in an on state and the boom switching valve (18) is in the first operating position, hydraulic oil in a rodless chamber of the boom cylinder (27) is replenished to a rod chamber of the boom cylinder (27) through the first oil passage (L6), the regeneration valve (4), the second branch oil passage (L72), and the boom switching valve (18) in this order.

5. The excavator energy recovery system of claim 2, further comprising a flow regulating valve (17) provided on the second oil supply path (L2) between the second main pump (23) and the boom switching valve (18) and configured to regulate a flow into the boom switching valve (18).

6. The excavator energy recovery system of claim 5, further comprising: a pilot pump (24) having a pilot oil supply passage (L4) and a pilot oil return passage (L5); the flow rate regulating valve (17) includes:

an oil inlet of the third one-way valve (171) is communicated with the second oil supply oil path (L2), an oil outlet of the third one-way valve (171) is communicated with an oil supply port of the movable arm reversing valve (18), and the third one-way valve (171) is provided with a spring cavity; and

the hydraulic control adjusting valve (172) is in a connection state and a disconnection state, an oil inlet of the hydraulic control adjusting valve (172) is communicated with the spring cavity, an oil outlet of the hydraulic control adjusting valve (172) is communicated with an oil supply port of the movable arm reversing valve (18), the hydraulic control adjusting valve (172) is provided with a first hydraulic control end (A) and a second hydraulic control end (B), the first hydraulic control end (A) is communicated with the pilot oil return path (L5), and the second hydraulic control end (B) is communicated with the pilot oil supply path (L4) through a first reversing valve (16).

7. The excavator energy recovery system of claim 2, wherein the boom directional control valve (18) has a third pilot controlled end (C) and a fourth pilot controlled end (D); the excavator energy recovery system further comprises:

a first proportional regulating valve (13) configured to regulate a pilot oil pressure of the third pilot control port (C); and

a second proportional regulating valve (14) configured to regulate a pilot oil pressure of the fourth hydraulic control port (D).

8. The excavator energy recovery system of any one of claims 1 to 7, further comprising: the confluence valve (3) is in a connection state and a disconnection state, an oil inlet of the confluence valve (3) is communicated with the first oil supply path (L1), and an oil outlet of the confluence valve (3) is communicated with an oil inlet of the movable arm descending valve (5), an oil inlet of the regeneration valve (4) and a rodless cavity of the movable arm oil cylinder (27);

the oil passing amounts of the movable arm descending valve (5) and the flow converging valve (3) are adjustable.

9. The excavator energy recovery system of claim 8, wherein the boom lowering valve (5) has a fifth hydraulic control end (E) and a sixth hydraulic control end (F), the confluence valve (3) has a seventh hydraulic control end (G) and an eighth hydraulic control end (H), the excavator energy recovery system further comprising:

a pilot pump (24) having a pilot oil supply passage (L4) and a pilot oil return passage (L5);

a third proportional regulating valve (7) configured to regulate a pressure of the fifth hydraulic control end (E) of the boom lowering valve (5), the fifth hydraulic control end (E) being connected to the pilot oil supply passage (L4), and the sixth hydraulic control end (F) being connected to the pilot oil return passage (L5); and

a fourth proportional regulating valve (6) configured to regulate a pressure of the eighth hydraulic control end (H) of the confluence valve (3), the seventh hydraulic control end (G) being connected with the pilot oil return path (L5), and the eighth hydraulic control end (H) being connected with the pilot oil supply path (L4).

10. The excavator energy recovery system of claim 1, further comprising:

an arm cylinder (28);

a first arm selector valve (9) provided on the first oil supply passage (L1) and configured to control the arm cylinder (28) to extend and retract; and

and a second arm switching valve (31) provided in the second oil supply path (L2) and configured to control the extension and contraction of the arm cylinder (28).

11. The excavator energy recovery system according to claim 10, wherein the first arm reversing valve (9) and the second arm reversing valve (31) are both provided with a first oil return port (T1) and a second oil return port (T2), a first throttling element (91) is connected between the first oil return port (T1) and the second oil return port (T2) of the first arm reversing valve (9) at a middle position (W2), and a first branch oil return path (L31) and a second branch oil return path (L32) are provided in the main oil return path (L3) downstream of the oil outlet of the boom lowering valve (5); wherein,

a radiator (29) is arranged on the first branch oil return path (L31), and the first branch oil return path (L31) is connected with an oil tank (30) through the radiator (29); the second branch oil return path (L32) sequentially passes through the first oil return port (T1), the first throttling element (91) and the second oil return port (T2) to be connected with the oil tank (30), the first oil return port (T1) of the second bucket rod reversing valve (31) is communicated with the first branch oil return path (L31), and the second oil return port (T2) of the second bucket rod reversing valve (31) is communicated with the second branch oil return path (L32).

12. The excavator energy recovery system of claim 11, wherein the first arm reversing valve (9) and the second arm reversing valve (31) are provided with an oil supply port (P), a first working oil port (M), a second working oil port (N) and a third working oil port (O);

when the first bucket rod reversing valve (9) is located at an inward contraction working position (W1), a first working oil port (M) is communicated with an oil supply port (P) and a rodless cavity of the bucket rod oil cylinder (28), a second working oil port (N) is communicated with a rod cavity of the bucket rod oil cylinder (28), and a third working oil port (O) is communicated with the second working oil port (N);

when the second bucket rod reversing valve (31) is located at the middle position (W2), a first working oil port (M) of the second bucket rod reversing valve (31) is communicated with a rodless cavity of the bucket rod oil cylinder (28), a second working oil port (N) of the second bucket rod reversing valve (31) is communicated with a third working oil port (O) of the first bucket rod reversing valve (9), and is communicated with the first working oil port (M) of the second bucket rod reversing valve (31) through a second throttling element (311), and the third working oil port (O), an oil supply port (P), a first oil return port (T1) and a second oil return port (T2) of the second bucket rod reversing valve (31) are all cut off.

13. The excavator energy recovery system of claim 11, wherein the first arm reversing valve (9) and the second arm reversing valve (31) are each provided with an oil supply port (P), a first working oil port (M), a second working oil port (N) and a third working oil port (O);

when first fill pole switching-over valve (9) are in adduction position (W1), first work hydraulic fluid port (M) with supply oil mouth (P) with the no pole chamber intercommunication of arm cylinder (28), second work hydraulic fluid port (N) with there is the pole chamber intercommunication of arm cylinder (28), third work hydraulic fluid port (O) with second work hydraulic fluid port (N) intercommunication, just third work hydraulic fluid port (O) passes through meso position (W2) of second arm switching-over valve (31) make hydraulic oil return the no pole chamber of arm cylinder (28).

14. The energy recovery system of the excavator according to claim 13, wherein when the second arm reversing valve (31) is in the first inward-retracted working position (W4), the oil supply port (P) of the second arm reversing valve (31) is communicated with the rodless cavity of the arm cylinder (28) through a first working oil port (M), a second working oil port (N) of the second arm reversing valve (31) is communicated with a third working oil port (O) of the first arm reversing valve (9), and is communicated with a first oil return port (T1) of the first branch oil return path (L31) connected to the second arm reversing valve (31), and a third throttling element (312) is arranged between the second working oil port (N) of the second arm reversing valve (31) and the first oil return port (T1).

15. The energy recovery system of the excavator according to claim 13, wherein when the second arm reversing valve (31) is in the second inward-retracting working position (W5), an oil supply port (P) of the second arm reversing valve (31) is communicated with the rodless cavity of the arm cylinder (28) through a first working oil port (M), a second working oil port (N) of the second arm reversing valve (31) is communicated with a third working oil port (O) of the first arm reversing valve (9) and is communicated with a first return oil port (T1) of the first arm reversing valve (31) to which the second arm reversing valve (31) is connected, a third throttling element (312) and a sixth check valve (315) are provided between the second working oil port (N) and the first return oil port (T1) of the second arm reversing valve (31), and the sixth check valve (315) is configured to allow only hydraulic oil to flow from the second working oil port (N) to the first return oil port (T1), and the second check valve (31) is communicated with the second working oil port (O) of the second arm reversing valve (31).

16. The excavator energy recovery system of claim 14 or 15, wherein when the second arm reversing valve (31) is in the first and second inward retracted working positions (W4, W5), a fourth check valve (313) is provided on an oil path between the first working oil port (M) and the second working oil port (N) of the second arm reversing valve (31) and configured to allow only oil to flow from the second working oil port (N) to the first working oil port (M).

17. An excavator comprising an excavator energy recovery system as claimed in any one of claims 1 to 16.